A 14-year-old female student died of an apparent self-inflicted gunshot wound Thursday after shooting and injuring another female student inside a high school in West Texas, according to the local sheriff.

Authorities did not release a possible motive for the gunfire that erupted shortly before 9 a.m. at Alpine High School in Alpine, a town of 5,900 about 220 miles southeast of El Paso.

"We're still in shock," Brewster County Sheriff Ronny Dodson said at an afternoon news conference.

The sheriff said the family of the girl who died had moved to the Alpine area about six months ago.

Dodson earlier told radio station KVLF that the injured student ran outside seeking help and was taken to a hospital with injuries that weren't considered life threatening.

Dodson said a federal law enforcement officer who was responding to the incident was shot in the leg when another officer's gun accidentally discharged. The federal officer was transported to a hospital in Odessa, Texas.

The shooting prompted a lockdown at Alpine's three public schools, which were later evacuated.

The school district declined comment, saying it would release a statement later. Alpine police referred to its Facebook page for updates, but none had been posted as of Thursday afternoon.

Law enforcement officials were also dealing with a series of bomb threats made in the wake of the shooting. They said they don't believe there was a connection between the threats and the shooting at the high school.

Authorities said threats were phoned in to Sul Ross State University and an Alpine hospital. There was also a threat at a motel in Marathon, Texas, about 30 miles east of Alpine.

"Right now, we have a nut," Dodson said at the news conference, adding, "Basically, he's what we're looking for right now."

Texas Attorney General Ken Paxton said earlier that he's monitoring developments in the Alpine shooting and promised to provide support for law enforcement agencies investigating the matter.